The urgent need to develop new therapies for treating both sensitive and especially resistant strains of Mycobacterium tuberculosis requires to return to basic research to explain the failures of existing treatments and identify new drug targets. Several well-established anti-tuberculosis agents, such as isoniazid and ethionamide are known to inhibit mycolic acid biosynthesis. As a consequence, a continuing biochemical study coupled with a molecular genetic approach into the anabolic pathway of mycolic acids should provide further fruitful leads in drug discovery in this application. Our immediate goals are to define, dissect, and characterize the mycolate synthase complex through the use of sub- cellular fractionation and solubilization of the activity; to purify individual enzymes and to assay for potential inhibitors of mycolate biosynthesis; to examine the complex mechanism of mycolic acid transport and the mode of action of known anti-tuberculosis drugs; and to synthesize novel structurally related therapeutic agents as custom designed inhibitors of mycolic acid biosynthesis with a view toward complementary structure-based design. Specifically, we shall study the pathway from Claisen-type condensation to final deposition of mycolic acids into cell wall components. The combined efforts of this highly experienced consortium should provide the means to solve some of the problems associated with drug resistance through understanding how mycolic acids are synthesized and providing highly developed enzymatic screens for inhibitors of mycolate biosynthesis.